Particularly in aircraft construction there has been for some time now increased investigation into the practicability of profiled structural parts of knitted fiber fabrics, by which are meant glass-fiber-reinforced (GFR) or carbon-fiber-reinforced (CFR) woven, nonwoven or knitted fabrics in for example mat- or band form. To form a profiled structural part of fiber composite material the fibers first have to be prefabricated and aligned in accordance with their required orientation. The prefabricated woven, nonwoven or knitted fabrics then have to be placed layer by layer, i.e. draped, into the desired mold. Particularly in the case of curved profiled structures this draping process is difficult and correspondingly laborious. In order to achieve curved geometries, the knitted fiber fabrics because of the differences in length between the outside edge and the inside edge have to be laid in arcs, which may lead to undesirable crease formation. A further difficulty is to observe the desired fiber orientation on the mold.
After draping, the multi-layer laminate structure obtained is fixed. This is effected conventionally in a so-called preform step, in which the laminate structure, powdered with a binding material that has a fixing effect deployed as a rule by the application of heat, is heated in order to cure the binding material. Alternatively, woven, nonwoven or knitted fabrics already impregnated with a binding material, so-called prepregs, may be used.
An application example of future profiled structural parts of fiber composite material are frames, such as are used in the fuselage and wings of an aircraft. Up till now, such frames manufactured from knitted fiber fabrics have had to be manufactured in a time-consuming manner by draping the individual woven layers carefully by hand onto an appropriate mold, where they are provisionally fixed and then baked by the application of heat into a preform. If frames made from knitted fiber fabrics are to be used in future in series aircraft construction, such a method of manufacture is too slow and too costly.